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Abstract:

Earphone plugging and unplugging detection circuits are disclosed in the
present invention, wherein one of the circuits includes a left sound
channel (L) pin, a first pin which can be connected and disconnected with
the L pin, a right sound channel (R) pin, and a second pin which can be
connected and disconnected with the R pin; the circuit also includes a
left detection signal line which is connected with the first pin, the
left detection signal line is connected or configured with a pull-up
resistor, the first pin is electrically connected with the second pin,
and the L pin and the R pin are connected with a pull-down resistor
respectively. The present invention not only has the advantages of having
simple circuit, small area occupied by PCB and low hardware cost, but
also can effectively improve the reliability of the earphone plugging and
unplugging detection.

Claims:

1. An earphone plugging and unplugging detection circuit, wherein, the
circuit comprises: a left sound channel (L) pin, a first pin which can be
connected and disconnected with the L pin, a right sound channel (R) pin,
and a second pin that can be connected and disconnected with the R pin,
wherein: the circuit also comprises a left detection signal line
connected to said first pin, the left detection signal line is connected
or configured with a pull-up resistor, said first pin is electrically
connected with said second pin, and the L pin and the R pin are
respectively connected with a pull-down resistor.

2. The circuit of claim 1, wherein: when the resistance of the pull-up
resistor and the pull-down resistor makes the L pin connected with the
first pin and/or the R pin connected with the second pin, the left
detection signal line is pulled down to a low level, and when the L pin
is disconnected with the first pin and the R pin is disconnected with the
second pin, the left detection signal line is pulled up to a high level.

3. An earphone plugging and unplugging detection circuit, wherein, the
circuit comprises: a left sound channel (L) pin, a first pin which can be
connected and disconnected with the L pin, a right sound channel (R) pin,
and a second pin which can be connected and disconnected with the R pin,
wherein: the circuit also comprises a left detection signal line
connected to said first pin, the left detection signal line is connected
or configured with a pull-down resistor, said first pin is electrically
connected with said second pin, and the L pin and the R pin are connected
with a pull-up resistor respectively.

4. The circuit of claim 3, wherein: when the resistance of the pull-up
resistor and the pull-down resistor makes the L pin connected with the
first pin and/or the R pin connected with the second pin, the left
detection signal line is pulled up to a high level, and when the L pin is
disconnected with the first pin and the R pin is disconnected with the
second pin, the left detection signal line is pulled down to a low level.

5. The circuit of claim 4, wherein: the pull-up resistor respectively
connected with the L pin and the R pin is larger than 9 to 10 times of an
earphone coil resistor.

6. An earphone plugging and unplugging detection circuit, the circuit
comprising: a left sound channel (L) pin, a first pin which can be
connected and disconnected with the L pin, a right sound channel (R) pin
and a second pin which can be connected and disconnected with the R pin,
wherein: the circuit also comprises a left detection signal line
connected with said first pin and a right detection signal line connected
with the second pin, the left detection signal line and the right
detection signal line are connected or configured with a pull-up resistor
respectively, and the L pin and the R pin are connected with a pull-down
resistor respectively.

7. The circuit of claim 6, wherein: when the resistance of the pull-up
resistor and the pull-down resistor makes the L pin connected with the
first pin, the left detection signal line is pulled down to a low level,
and when the L pin is disconnected with the first pin, the left detection
signal line is pulled up to a high level, moreover, the right detection
signal line is pulled down to the low level when the R pin is made
connected with the second pin, and the right detection signal line is
pulled up to the high level when the R pin is disconnected with the
second pin.

8. An earphone plugging and unplugging detection circuit, the circuit
comprising: a left sound channel (L) pin, a first pin which can be
connected and disconnected with the L pin, a right sound channel (R) pin
and a second pin which can be connected and disconnected with the R pin,
wherein: the circuit also comprises a left detection signal line
connected with said first pin and a right detection signal line connected
with the second pin, the left detection signal line and the right
detection signal line are connected or configured with a pull-down
resistor respectively, and the L pin and the R pin are connected with a
pull-up resistor respectively.

9. The circuit of claim 8, wherein: when the resistance of the pull-up
resistor and the pull-down resistor makes the L pin connected with the
first pin, the left detection signal line is pulled up to a high level;
when the L pin is disconnected with the first pin, the left detection
signal line is pulled down to a low level; moreover, the right detection
signal line is pulled up to a high level when the R pin is connected with
the second pin, and the right detection signal line is pulled down to the
low level when the R pin is disconnected with the second pin.

10. The circuit of claim 9, wherein: the pull-up resistor respectively
connected with the L pin and the R pin is larger than 9 to 10 times of an
earphone coil resistor.

Description:

TECHNICAL FIELD

[0001] The present invention relates to the field of terminal device
technologies, and more especially, to an earphone plugging and unplugging
detection circuit.

BACKGROUND OF THE RELATED ART

[0002] The earphone has become a standard configured attachment of the
terminal product. When the earphone is used, it usually requires that the
terminal product automatically recognize the earphone plugging and
unplugging state. Therefore, it needs to use the earphone plugging and
unplugging detection circuit. The forms of the earphone plugging and
unplugging detection circuit are various, and the spring leaf-type
earphone plugging and unplugging detection circuit has the advantages of
having simple circuit, low cost, and small area occupied by the Printed
Circuit Board (PCB), and thus is widely used.

[0003] FIG. 1 is a schematic diagram of the definitions of the
four-segment earphone plug and socket pin, and there are two types of
four-segment earphone plugs: 3.5 mm and 2.5 mm, the definitions of the
plug pins are: from the root to the end, ground (GND), microphone (MIC),
right sound channel (R) and left sound channel (L). The three-segment
earphone plug differs from the four-segment earphone plug in that the
three-segment earphone plug does not have the MIC pin. The pins of the
four-segment earphone socket pins are defined as comprising: the ground
(GND) 1, the right sound channel 2 (R), the second pin 3 that forms a
normally closed connection with the pin 2, the left sound channel 5 (L),
and the first pin 4 that forms a normally closed connection with the pin
5, and the microphone 6 (MIC). The difference between the three-segment
earphone socket and the four-segment earphone socket is that the
three-segment earphone socket does not have the microphone (MIC) pin.

[0004] At present, a pair of mechanical spring leaves such as the pin 4
and the pin 5 that forms a normally closed connection with the pin 4
inside the earphone socket are used to implement the earphone plugging
and unplugging detection. When the earphone is plugged in, the pin 5 is
disconnected, and is electrically disconnected with the pin 4, thus an
interruption is formed in the hardware and is reported to the control
circuit, and the terminal equipment enables the interruption service
routine. When the earphone is unplugged, the control circuit detects the
earphone unplugging and exits from the service routine. The earphone
plugging and unplugging makes the pin 4 connected and disconnected with
the pin 5 of the earphone socket. Therefore, whether the state of
earphone plugging and unplugging is able to be correctly detected is
closely related to the mechanical spring leaves inside the earphone
socket. When the earphone socket has a quality problem, for example, the
pin 4 and the pin 5 should be normally closed but actually they are not,
it will cause the controller to mistakenly judge that there are earphones
plugged in, the earphone symbol appears in the terminal product, and
meanwhile the audio path is switched to the earphone end, causing the
entire terminal product to be in the silent mode, which seriously affects
the normal use.

SUMMARY OF THE INVENTION

[0005] The technical problem to be solved in the present invention is to
provide an earphone plugging and unplugging detection circuit to more
reliably detect the states of earphone plugging and unplugging.

[0006] To solve the aforementioned technical problem, the present
invention provides an earphone plugging and unplugging detection circuit.
The circuit comprises: a left sound channel (L) pin, a first pin which
can be connected and disconnected with the L pin, a right sound channel
(R) pin, and a second pin that can be connected and disconnected with the
R pin, wherein:

[0007] the circuit also comprises a left detection signal line connected
to said first pin, the left detection signal line is connected or
configured with a pull-up resistor, the first pin is electrically
connected with the second pin, and the L pin and the R pin are
respectively connected with a pull-down resistor.

[0008] When the resistance of the pull-up resistor and the pull-down
resistor makes the L pin connected with the first pin and/or the R pin
connected with the second pin, the left detection signal line is pulled
down to a low level, and when the L pin is disconnected with the first
pin and the R pin is disconnected with the second pin, the left detection
signal line is pulled up to a high level.

[0009] To solve the aforementioned technical problem, the present
invention also provides an earphone plugging and unplugging detection
circuit, the circuit comprising: a left sound channel (L) pin, a first
pin which can be connected and disconnected with the L pin, a right sound
channel (R) pin, and a second pin which can be connected and disconnected
with the R pin, wherein:

[0010] The circuit might also comprise a left detection signal line
connected to said first pin, the left detection signal line is connected
or configured with a pull-down resistor, said first pin is electrically
connected with said second pin, and the L pin and the R pin are connected
with a pull-up resistor respectively.

[0011] When the resistance of the pull-up resistor and the pull-down
resistor makes the L pin connected with the first pin and/or the R pin
connected with the second pin, the left detection signal line is pulled
up to a high level, and when the L pin is disconnected with the first pin
and the R pin is disconnected with the second pin, the left detection
signal line is pulled down to a low level.

[0012] The pull-up resistor respectively connected with the L pin and the
R pin is larger than 9 to 10 times of an earphone coil resistor.

[0013] To solve the aforementioned technical problem, the present
invention also provides an earphone plugging and unplugging detection
circuit, the circuit comprising: a left sound channel (L) pin, a first
pin which can be connected and disconnected with the L pin, a right sound
channel (R) pin and a second pin which can be connected and disconnected
with the R pin, wherein:

[0014] the circuit might also comprise a left detection signal line
connected with said first pin and a right detection signal line connected
with the second pin, the left detection signal line and the right
detection signal line are connected or configured with a pull-up resistor
respectively, and the L pin and the R pin are connected with a pull-down
resistor respectively.

[0015] When the resistance of the pull-up resistor and the pull-down
resistor makes the L pin connected with the first pin, the left detection
signal line is pulled down to a low level, and when the L pin is
disconnected with the first pin, the left detection signal line is pulled
up to a high level. Moreover, the right detection signal line is pulled
down to the low level when the R pin is made connected with the second
pin, and the right detection signal line is pulled up to the high level
when the R pin is disconnected with the second pin.

[0016] To solve the aforementioned technical problem, the present
invention also provides an earphone plugging and unplugging detection
circuit, the circuit comprising: a left sound channel (L) pin, a first
pin which can be connected and disconnected with the L pin, a right sound
channel (R) pin and a second pin which can be connected and disconnected
with the R pin, wherein:

[0017] the circuit might also comprise a left detection signal line
connected with said first pin and a right detection signal line connected
with the second pin, the left detection signal line and the right
detection signal line are connected or configured with a pull-down
resistor respectively, and the L pin and the R pin are connected with a
pull-up resistor respectively.

[0018] When the resistance of the pull-up resistor and the pull-down
resistor makes the L pin connected with the first pin, the left detection
signal line is pulled up to a high level; when the L pin is disconnected
with the first pin, the left detection signal line is pulled down to a
low level; moreover, the right detection signal line is pulled up to a
high level when the R pin is connected with the second pin, and the right
detection signal line is pulled down to the low level when the R pin is
disconnected with the second pin.

[0019] The pull-up resistor respectively connected with the L pin and the
R pin is larger than 9 to 10 times of an earphone coil resistor.

[0020] In summary, the present invention not only has the advantages of
having simple circuit, small area occupied by the PCB and low hardware
cost, but also can effectively improve the reliability of the earphone
plugging and unplugging detection.

BRIEF DESCRIPTION OF DRAWINGS

[0021] FIG. 1 is a schematic diagram of the definition of the four-segment
earphone plug and socket pins in the prior art;

[0022] FIG. 2 is a schematic diagram of a first embodiment of the earphone
plugging and unplugging detection circuit in accordance with the present
invention;

[0023]FIG. 3 is a schematic diagram of a second embodiment of the
earphone plugging and unplugging detection circuit in accordance with the
present invention;

[0024] FIG. 4 is a schematic diagram of a third embodiment of the earphone
plugging and unplugging detection circuit in accordance with the present
invention;

[0025]FIG. 5 is a schematic diagram of a fourth embodiment of the
earphone plugging and unplugging detection circuit in accordance with the
present invention.

PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

[0026] The present invention will be described in detail below with
reference to the accompanying drawings. It should be noted that without
conflict, the embodiments in this application and the characteristics of
the embodiments can be combined randomly with each other.

[0027] The First Embodiment:

[0028] FIG. 2 shows an earphone plugging and unplugging detection circuit
in the present invention, comprising: the L pin 5, the first pin 4 that
forms a normally closed connection with the L pin 5, the R pin 2, the
second pin 3 that forms a normally closed connection with the R pin 2,
and the left detection signal line connected with the first pin 4, where
the left detection signal line is connected or configured with the
pull-up resistor R1, the first pin 4 is electrically connected with the
second pin 3, and the L pin 5 and the R pin 2 are connected with a
pull-down resistor respectively.

[0029] The resistor R1 connected with the left detection signal line is a
pull-up resistor, and if the left detection signal line can internally
configure a pull-up resistor, the R1 can be removed. The R1 and the
pull-down resistor R3 connected with the left channel output (L_OUT)
signal line as well as the pull-down resistor R2 connected with the right
channel output (R_OUT) signal line constitute a voltage divider circuit,
and moreover, the pull-down capabilities of the R2 and the R3 are much
stronger than the pull-up capability of the R1 such that when the
earphones are not plugged in, the left detection signal line is at the
low level, if the resistance of the R1 is at least 10 times of the R2 and
the R3, for example, the resistance of the R1 is 100 KΩ, and the
resistance of the R2 and the R3 is 10 KΩ. Here it does not limit to
more than 10 times, and a value, such as 9 times, 9.5 times, and so on,
can be chosen based on experience.

[0030] The second pin 3 and the first pin 4 of the earphone socket are
electrically connected together. When the earphones are plugged in, the R
pin 2 and the L pin 5 of the earphone socket are disconnected, and
disconnected electrically with the second pin 3 and the first pin 4
respectively, the pull-down resistors R2 and R3 do not work, the pull-up
resistor R1 pulls the left detection signal line up to the high level,
forming a hardware interruption, and the earphone plugging is detected.
The earphone unplugging is an opposite process. When a pair of the R pin
2 and the second pin 3 or the first pin 4 and the L pin 5 do not form a
normal close due to the quality problem of the earphone socket, while the
other pair can still work normally, for example, the normal close of the
first pin 4 and the L pin 5 fails, while the R1 and the R2 can share
partial voltage via the normally closed R pin 2 and second pin 3, and the
R pin 2 is disconnected and disconnected electrically with the second pin
3 when the earphones are plugged in, the left detection signal line is
pulled up to the high level, forming a hardware interruption, and the
earphone plugging is detected. The earphone unplugging is an opposite
process. It can be seen that the detection circuit only requires one
group of normally closed pins, which provides the reliability of the
earphone plugging and unplugging detection.

[0031] The Second Embodiment:

[0032]FIG. 3 shows an earphone plugging and unplugging detection circuit
in the present invention, the circuit comprising: the L pin 5, the first
pin 4 which can be connected and disconnected with the L pin 5, the R pin
2, the second pin 3 which can be connected and disconnected with the R
pin 2, and the left detection signal line connected with the first pin 4,
where the left detection signal line is connected or configured with the
pull-down resistor R1, the first pin 4 is electrically connected with the
second pin 3, the L pin 5 and the R pin 2 are connected with the pull-up
resistors R3 and R2 respectively.

[0033] The resistor R1 connected with the left detection signal line is a
pull-down resistor, and if the left detection signal line can internally
configure a pull-down resistor, the R1 can be removed. The R1 and the
pull-up resistor R3 connected with the left channel output (L_OUT) signal
line as well as the pull-up resistor R2 connected with the right channel
output (R_OUT) signal line constitute a voltage divider circuit, and
moreover, the pull-up capabilities of the pull-up resistors R2 and the R3
are much stronger than the pull-down capability of the pull-down R1 such
that when the earphones are not plugged in, the left detection signal
line is at the high level, and meanwhile, the resistance of the R2 and
the R3 is preferably greater than 9-10 times of 32Ω (the earphone
coil resistor), to avoid sharing the current of the earphone heavily in
the earphone plug-in state, which affects the earphone effect.

[0034] When the earphones are plugged in, the R pin 2 and the L pin 5 of
the earphone socket are disconnected, and disconnected electrically with
the second pin 3 and the first pin 4 respectively, the pull-up resistors
R2 and R3 do not work, the pull-down resistor R1 pulls the left detection
signal line down to the low level, forming a hardware interruption, and
the earphone plugging is detected. The earphone unplugging is an opposite
process. The detection circuit only requires one group of normally closed
pins. For example, the normal close of the first pin 4 and the L pin 5
fails, while the R1 and the R2 can still share partial voltage via the
normally closed R pin 2 and second pin 3, and the R pin 2 is disconnected
and disconnected electrically with the second pin 3 when the earphones
are plugged in, the left detection signal line is pulled up to the high
level, forming a hardware interruption, and the earphone plugging is
detected. The earphone unplugging is an opposite process.

[0035] The Third Embodiment:

[0036] FIG. 4 shows an earphone plugging and unplugging detection circuit
in the present invention, the circuit comprising: the L pin 5, the first
pin 4 which can be connected and disconnected with the L pin 5, the R pin
2, the second pin 3 which can be connected and disconnected with the R
pin, the left detection signal line connected with the first pin 4, and
the right detection signal line connected with the second pin 3, where
the left detection signal line and the right detection signal line are
connected or configured with a pull-up resistor respectively, and the L
pin and the R pin are connected with a pull-down resistor respectively.

[0037] The resistor R1 connected with the left detection signal line is a
pull-up resistor, and if the left detection signal line can internally
configure a pull-up resistor, the R1 can be removed. The R1 and the
pull-down resistor R3 connected with the left channel output (L_OUT)
signal line can form a voltage divider circuit via the normally closed
first pin 4 and L pin 5. The pull-up resistor connected with the right
detection signal line is R4, and if the right detection signal line can
internally configure a pull-up resistor, the R4 can be removed. The R4
and the pull-down resistor R2 on the right channel output (R_OUT) signal
line form a voltage divider circuit via the normally closed R pin 2 and
second pin 3, and moreover, the pull-down capabilities of the R2 and the
R3 are much stronger than the pull-up capabilities of the R1 and R4 such
that when the earphones are not plugged in, the left detection signal
line and the right detection signal line are both pulled down to the low
level.

[0038] When the earphones are plugged in, the R pin 2 and the L pin 5 of
the earphone socket are disconnected, and disconnected electrically with
the second pin 3 and the first pin 4 respectively, the pull-down
resistors R2 and R3 do not work, the pull-up resistor R1 pulls both the
left detection signal line and the right detection signal line up to the
high level, forming a hardware interruption, and the earphone plugging is
detected. The earphone unplugging is an opposite process. When a pair of
the normally closed pins fails, one of the detection pins is at the high
level, while the other one is at the low level, at which moment, the
control circuit considers that there is no earphone plugged in. When the
earphones are plugged in, the pair of still working earphone spring
leaves are disconnected and separated with each other electrically, at
which moment, both the two detection pins are at the high level, and the
control circuit considers that there are earphones plugged in, and the
earphones are detected. It can be seen that when a pair of normally
closed pins fails, the detection circuit can still correctly detect the
plugging and unplugging of the earphones, which effectively improves the
reliability of the earphone plugging and unplugging.

[0039] The Fourth Embodiment:

[0040]FIG. 5 shows an earphone plugging and unplugging detection circuit
in the present invention, the circuit comprising: the L pin 5, the first
pin 4 which can be connected and disconnected with the L pin 5, the R pin
2, the second pin 3 which can be connected and disconnected with the R
pin 2, the left detection signal line connected with the first pin 4, and
the right detection signal line connected with the second pin 3, where
the left detection signal line and the right detection signal line are
connected or configured with a pull-down resistor respectively, and the L
pin 5 and the R pin 2 are connected with a pull-up resistor respectively.

[0041] The resistor R1 connected with the left detection signal line is a
pull-down resistor, and if the left detection signal line can internally
configure a pull-down resistor, the R1 can be removed. The R1 and the
pull-up resistor R3 connected with the left channel output (L_OUT) signal
line can form a voltage divider circuit. The pull-down resistor connected
with the right detection signal line is R4, and if the right detection
signal line can internally configure a pull-down resistor, the R4 can be
removed. The R4 and the pull-up resistor R2 on the right channel output
(R_OUT) signal line form a voltage divider circuit, and moreover, the
pull-up capabilities of the R2 and the R3 are much stronger than the
pull-up capabilities of the R1 and R4 such that when the earphones are
not plugged in, the left detection signal line and the right detection
signal line are both pulled up to the high level. Meanwhile, the
resistance of the R2 and the R3 is preferably greater than 9-10 times of
32Ω (the earphone coil resistor), to avoid sharing the current of
the earphone heavily in the earphone plug-in state, which affects the
earphone effect.

[0042] When the earphones are plugged in, the R pin 2 and the L pin 5 of
the earphone socket are disconnected, and disconnected electrically with
the second pin 3 and the first pin 4, the pull-up resistors R2 and R3 do
not work, the pull-down resistor pulls the left detection signal line and
the right detection signal line down to the low level, forming a hardware
interruption, and the earphone plugging is detected. The earphone
unplugging is an opposite process. When a pair of the normally closed
pins does not work, one of the detection pins is the low level, while the
other one is the high level, at which moment, the control circuit
considers that there are no earphones plugged in. When the earphones are
plugged in, the pair of still working earphone spring leaves are
disconnected and separated with each other electrically, at which moment,
both the two detection pins are at the low level, the control circuit
considers that there are earphones plugged in, and the earphones are
detected. It can be seen that when a pair of normally closed pins fails,
the detection circuit can still correctly detect the plugging and
unplugging of the earphones, which effectively improves the reliability
of the plugging and unplugging of the earphones.

[0043] The embodiment also provides a terminal using the aforementioned
earphone plugging and unplugging detection circuit, the earphone plugging
and unplugging detection circuit is set in the shell of the terminal, and
the structure of the earphone plugging and unplugging detection circuit
is as described above and thus will not be discussed here.

[0044] The two-spring leave earphone plugging and unplugging detection
circuit also can be applied to an earphone socket having two pairs of
normally opened pins, with the principle being similar. The forms of the
above circuits can all improve the reliability of the earphone plugging
and unplugging detection, and since the first embodiment occupies few
resources and has a relatively simple circuit, the first embodiment is
preferred. Moreover, when the detection pins can internally configure a
pull-up or pull-down resistor, the pull-up or pull-down resistor on the
detection pins can be removed, thus further saving the PCB space and the
hardware costs.

[0045] The above description is of only the preferred embodiments of the
present invention and is not intended to limit the present invention. For
those skilled in the field, the present invention can have a variety of
changes and modifications. Without departing from the spirit and
principles of the present invention, any change, equivalent replacement
and improvement should be included within the protection scope of the
present invention.

INDUSTRIAL APPLICABILITY

[0046] The present invention not only has the advantages of having simple
circuit, small area occupied by the PCB and low hardware cost, but also
can effectively improve the reliability of the earphone plugging and
unplugging detection.